Abstract: In order that it may be possible to form a strong-electric-field region at a level at which a electromagnetic waves are easily absorbed by an object to be heated 20 with low power in an electromagnetic-wave heating device 10 for heating the object to be heated 20 utilizing an electromagnetic waves, the electromagnetic-wave heating device 10 comprises: an oscillator 21 for outputting an electromagnetic waves; and a radiation antenna 22 being a conductor that radiates the electromagnetic waves outputted from the oscillator 21 and having a resonance structure in which resonance occurs in the conductor by the electromagnetic waves in a frequency band transmitted from the oscillator 21, and is configured that a strong-electric-field region for heating the object to be heated is formed along the radiation antenna 22 by the electromagnetic waves supplied from the oscillator 21 to the radiation antenna 22.